Welcome to the World of Chemistry. The Language of Chemistry CHEMICAL ELEMENTS -CHEMICAL ELEMENTS - –pure substances that cannot be decomposed by ordinary.

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Presentation on theme: "Welcome to the World of Chemistry. The Language of Chemistry CHEMICAL ELEMENTS -CHEMICAL ELEMENTS - –pure substances that cannot be decomposed by ordinary."— Presentation transcript:

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The Language of Chemistry The elements, their names, and symbols are given on the PERIODIC TABLEThe elements, their names, and symbols are given on the PERIODIC TABLE How many elements are there?How many elements are there?

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The Periodic Table Dmitri Mendeleev ( )

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Glenn Seaborg ( ) Discovered 8 new elements.Discovered 8 new elements. Only living person for whom an element was named.Only living person for whom an element was named.

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Copper atoms on silica surface. See CD- ROM Screen 1.4 An atom is the smallest particle of an element that has the chemical properties of the element.An atom is the smallest particle of an element that has the chemical properties of the element. Distance across = 1.8 nanometer (1.8 x m)

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An atom consists of a nucleusnucleus –(of protons and neutrons) electrons in space about the nucleus.electrons in space about the nucleus. The Atom Electron cloud Nucleus

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The red compound is composed of nickel (Ni) (silver) carbon (C) (black) hydrogen (H) (white) oxygen (O) (red) nitrogen (N) (blue) CHEMICAL COMPOUNDS are composed of atoms and so can be decomposed to those atoms.

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A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound. Composition of molecules is given by a MOLECULAR FORMULA H2OH2OH2OH2O C 8 H 10 N 4 O 2 - caffeine

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The Nature of Matter Chemists are interested in the nature of matter and how this is related to its atoms and molecules. GoldMercury

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Chemistry & Matter We can explore the MACROSCOPIC world — what we can see —We can explore the MACROSCOPIC world — what we can see — to understand the PARTICULATE worlds we cannot see.to understand the PARTICULATE worlds we cannot see. We write SYMBOLS to describe these worlds.We write SYMBOLS to describe these worlds.

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Kinetic Nature of Matter Matter consists of atoms and molecules in motion.

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STATES OF MATTER SOLIDS — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement.SOLIDS — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement. –Reasonably well understood. LIQUIDS — have no fixed shape and may not fill a container completely.LIQUIDS — have no fixed shape and may not fill a container completely. –Not well understood. GASES — expand to fill their container.GASES — expand to fill their container. –Good theoretical understanding.

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Physical Properties What are some physical properties? colorcolor melting and boiling pointmelting and boiling point odorodor

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Physical Changes Some physical changes would be boiling of a liquidboiling of a liquid melting of a solidmelting of a solid dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.

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DENSITYDENSITY Density is an INTENSIVE property of matter.Density is an INTENSIVE property of matter. –does NOT depend on quantity of matter. –temperature Contrast with EXTENSIVEContrast with EXTENSIVE –depends on quantity of matter. –mass and volume. Styrofoam Brick

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PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg in grams? In pounds? Solve the problem using DIMENSIONAL ANALYSIS.

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Chemical Properties and Chemical Change Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules. Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.

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Types of Observations and Measurements We make QUALITATIVE observations of reactions — changes in color and physical state.We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE MEASUREMENTS, which involve numbers.We also make QUANTITATIVE MEASUREMENTS, which involve numbers. Use SI units — based on the metric systemUse SI units — based on the metric system